arc: Avoid showing browser window in ARC++ Kiosk session

chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc

Index: chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc
diff --git a/chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc b/chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc
index c7c0dba2bae08f4e722a6243cf40b7f615e45116..c15fdb3b824d58d2cdeaf3aa4c963d1dc53688ec 100644
--- a/chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc
+++ b/chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc
@@ -883,6 +883,7 @@ void ChromeUserManagerImpl::ArcKioskAppLoggedIn(user_manager::User* user) {
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
   command_line->AppendSwitch(chromeos::switches::kEnableArc);
   command_line->AppendSwitch(::switches::kForceAndroidAppMode);
+  command_line->AppendSwitch(::switches::kSilentLaunch);
 
   // Disable window animation since kiosk app runs in a single full screen
   // window and window animation causes start-up janks.